add dockerhub-demo jenkinsfile and add version to dockerfile (#17)

* add dockerhub-demo jenkinsfile and add version to dockerfile

* library is loaded in implicitly

* needed to use double quotes on push

* commenting out push for now

* commenting out push for now

* added repo to hub

* separate build and push stages

* formatting

Dockerfile

@@ -1,3 +1,3 @@
 FROM tomcat:9.0-alpine
-
+LABEL version = "1.1.2"
 COPY target/petclinic.war /usr/local/tomcat/webapps/petclinic.war

jenkinsfiles/dockerhub-demo

@@ -0,0 +1,38 @@
+pipeline {
+    agent none
+    stages {
+       stage('Build') {
+           agent {
+               docker {
+                   image 'maven:3.5.0'
+               }
+           }
+           steps {
+                   sh 'mvn clean install -DskipTests=true -B'
+           }
+       }
+       stage('Build container') {
+             agent any
+             steps {
+                 script {
+                     sh "docker build -t liatrio/petclinic-tomcat:${env.BRANCH_NAME} ."
+                     if ( ${env.BRANCH_NAME} == 'master' ) {
+                         def containerVersion = getVersionFromContainer("liatrio/petclinic-tomcat:${env.BRANCH_NAME}")
+                         failIfVersionExists("liatrio","petclinic-tomcat",containerVersion)
+                         sh "docker build -t liatrio/petclinic-tomcat:${containerVersion} ."
+                     }
+                 }
+             }
+       }
+       stage('Push to dockerhub') {
+           agent any
+           steps {
+                script {
+                    if ( ${env.BRANCH_NAME} == 'master' ) 
+                        sh "docker push liatrio/petclinic-tomcat:${containerVersion}"
+                    else sh "docker push  liatrio/petclinic-tomcat:${env.BRANCH_NAME}"
+                }
+           }
+       }
+   }
+}